I have heard that electricity comes directly from powerplants to our homes. No storage or battery of any kind. If I turn on an extra light, how does the powerplant adjust for such a small change in the demand? Does that mean every other device that is turned on and getting electricity from this powerplant gets a little less energy to compensate for my light?
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Very simply, every light you switch on increases the physical load that the generator must overcome to maintain the grid’s voltage.
Imagine a simple hand crank generator configured with a couple of switched lightbulbs that can be connected to the circuit independently.
As the power company, your job is to crank over the generator so the circuit produces 12 Volts at all times. With both lightbulbs disconnected, you don’t need much cranking force to make the generator produce 12 Volts. But as soon as you close a switch and connect the first lightbulb, the generator’s electricity has a new path to follow. Electricity flows through the lightbulb, and decreases the circuit’s Voltage.
Your duty to provide 12 Volts to the circuit means you must crank harder so the generator produces sufficent current to make up for the decrease in overall circuit resistance caused by opening an electrical path through the lightbulb. The required increase in current is inversely proportional to the lightbulb’s resistance.
Switch on the second lightbulb, and the force needed to keep everything at 12 Volts goes up again, because even more current must flow to “fill up” the electrical path opened by connecting the lightbulb.
In reality, electrical demand changes constantly. Powerplant generators are governed to maintain voltage. Slight drops in voltage cause the system to respond by applying more force to the generator so it can sustain voltage. Whatever current flows at that voltage represents total grid load.
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